The 20-year-old will sign a new two-and-a-half-year deal with Leeds next week.
Lees is currently on loan at League Two side Bury until January.
“I’m very pleased to be signing a new deal,” Lees told the club’s official website.
“I’ve been here for a long time and it’s a good feeling that it can last longer.
“It’s nice to know that they are looking to get me involved. It’s a chance for me to get better and progress.
“That’s what I’ve been aiming to do this season and I want to kick-on and play for the club.
“When I go back to Leeds, whether it’s January or the end of the season, I’ll give it my best shot to get in that squad.”
“Things are going well,” he continued. “This is my second loan – I was at Accrington last season – and I’m coming up for 75 games now.
“Last year I played right-back and this year I’ve played at centre-half. It’s a lot different at centre-half, it’s more of a challenge and it’s a more central role.
“I feel I’ve done okay at Bury. Things are going well in the league, and if people have been watching I hope they have liked what they have seen.
“It’s really good to be playing first-team football because you get game sharpness, fitness, and gain experience every week, especially at centre-half, playing against some good strikers. Trying to handle them and keep them quiet is a real hard task.
“I’m trying to focus on myself, play as well as I can and develop, because if I develop Leeds will benefit as well.”
